Invasive plants in wildflower mixes

UW study finds noxious weeds in seed packets

Published 10:00 pm, Thursday, April 18, 2002

With names like "meadow mixture," "wedding wildflowers" and "backyard biodiversity," you'd think packets of wildflower seeds would sprout nothing but a medley of fragrant blooms.

But when a student at the University of Washington's Center for Urban Horticulture grew 19 packets of wildflower seed mixes marketed in the Pacific Northwest, they found that each contained anywhere from three to 13 invasive species, and eight had seeds for plants considered noxious weeds in at least one state or Canadian province.

A third of the packets listed no contents, and only five of the packets correctly itemized the seeds they contained, the study found.

"I can't recommend using any wildflower seed mixes," said lead researcher Lorraine Brooks, who was an undergraduate studying environmental horticulture when she grew the plants from April to September 2001.

Brooks and Sarah Reichard, UW assistant professor of forest resources who supervised the research, say gardeners should buy wildflower seeds species by species, making sure they are native to the region, rather than buying seed mixes.

The study could be published as early as this spring or summer, Reichard said.

Several company officials reached Thursday said they are concerned by the findings and plan to look into why mixes may have contained invasive or noxious species.

Molbak's spokeswoman Peggy Campbell said the company no longer sells two mixes that researchers found to contain yellow toadflax -- listed as noxious in 14 states and provinces.

"We feel very strongly about being responsible gardeners," Campbell said.

"Every year, we take a look at product mixes and delete what may be new on the noxious weeds list."

Another noxious weed found in a mix produced by Ed Hume Seeds was dame's rocket, which is on Colorado's list of noxious weeds. An Ed Hume spokesman declined immediate comment, saying the company president was unavailable.

Plants are considered invasive if their spread overcomes other plants native to a particular ecosystem. Noxious weeds, often classified as such on state lists, are considered more destructive and difficult to control than invasive species.

According to the UW study, one of Nature's Garden Seed Co.'s mixes flowered nothing but invasive plants, even though it was labeled "native."

"Without further information regarding the study, it's hard for us to comment on the research," said Joan Goski, manager of Nature's Garden Seed Co., which had two seed mixes cited in the study.

"But we do stand by our products. We have really wonderful, reputable suppliers of all the seeds in those mixes."

Burpee Seeds and Plants spokesman Dave Devine said the company makes every effort to keep invasive or noxious weeds out of its products.

"We're a complete advocate of not spreading noxious weeds in areas where they don't belong," Devine said.

"We try to be very good stewards of not allowing that to happen. Just unfortunately, sometimes in the distribution (of seeds) that does happen."